Random function in Modelica

Question

Hello，I need a function as random in C language. Maybe you will say that i can call C function, but the effect is not the same in visual c++ tool. So, I need your help. thanks.

possible duplicate: http://stackoverflow.com/questions/36265293/assignment-problems-with-simple-random-number-generation-in-modelica — matth, Apr 01 '16 at 07:34

score 3 · Answer 1 · answered Mar 31 '16 at 13:50

3

See the Noise library:

https://github.com/DLR-SR/Noise

It has some models and functions to generate random numbers.

answered Mar 31 '16 at 13:50

Adrian Pop

4,034
13
16

Thanks, but i want it works like c: int res=random()%100; – Laughing Apr 11 '16 at 02:36
http://book.xogeny.com/behavior/functions/external/ I implemented it by C languge – Laughing Apr 11 '16 at 08:14

score 1 · Answer 2 · edited May 04 '16 at 14:04

If you are using Dymola, you can use the function rand():

model rand_model
  Real a(start=rand());
  Real b(start=rand());
equation 
  when (sample(1,1)) then
    a = rand();
    b = rand();
  end when;
end rand_model;

The function is not documented in the Dymola user manual and it is no part of the modelica standard. The output seems to be an integer between 0 and 32767, seed seems to be constant.

Perhaps the implementation is given in the moutil.c file which is shipped with Dymola. But i'm not sure.

Random function in Modelica

2 Answers2